The trend of continuous increase in human world population characterizing the past two millenia, underwent a phase shift in 1975 to a slower rate of increase. Peak world population will be attained in 2065 and there will follow a decline to the 1975 level by 2175. Thereafter, decline will continue at an even slower rate. Continuation of historical trends of population increase projects to an instantaneous increase to infinity. For the world this time varies between 2017 and 2026 A.D. Five major sets of regions of the world are characterized by the dates 1982, 1988, 2036, 2054 and 2140 when problems related to population density will become particularly critical.